If an interface between two incommensurate surfaces is atomically
clean, a state of virtually frictionless sliding is
anticipated, often referred to as ``superlubricity.'' Theory
predicts that the lattice mismatch at the interface causes a
decrease of shear stress with increasing contact area, ultimately
leading to vanishing friction. Analyzing the contact area
dependence of superlubric friction should therefore confirm the
concept of superlubricity. To measure the interfacial friction we
have manipulated metallic nanoparticles of different size on
atomically flat surfaces by contact mode atomic force
microscopy techniques. An optimized experimental setup allowed us
to quantify friction of nanoparticles which previously
appeared to be sliding frictionless [1]. As theoretically
expected, interfacial friction showed a nonlinear contact area
dependence with a shear stress decreasing with contact area. This
confirms the superlubric sliding of the nanoparticles under
investigation.
\\[4pt]
[1] Dietzel et al., Phys. Rev. Lett. 101, 125505 (2008).

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2010.MAR.L32.7